Melbourne airport terminal evacuated

Qantas's domestic terminal at Melbourne's Tullamarine Airport has been evacuated after a security breach.

Thousands of passengers were reportedly told to leave the building about 9.30am today after a man entered a secure part of the terminal and vanished.

Passengers already on board planes also had to evacuate.

The security scare delayed flights and hundreds of passengers will have to be rescreened.

Qantas said the man walked into the secure area by going through exit doors, and even though it is not thought he had suspicious intentions, the matter would be referred to the federal police.

"When you get off a flight and exit at the arrivals hall to collect bags, there are three doors, which you go through," Qantas spokesman Thomas Woodward was quoted as saying in The Age.

"A passenger has evidently, for whatever reason, gone through one of those doors and obviously hasn't been security screened at all, so unfortunately we're having to bring everyone back out from the secure areas for rescreening."

Woodward told the newspaper the man was spotted on closed circuit TV entering through the exit but security staff watching monitors lost track of him once inside the terminal.